1. Field of the Invention
The present invention relates to an apparatus for feeding a solid film-formation material.
Priority is claimed on Japanese Patent Application No. 2007-263249, filed Oct. 9, 2007, the contents of which are incorporated herein by reference.
2. Description of Related Art
A perovskite material (e.g., SrTiO) is anticipated as the next-generation high-dielectric-constant film, and a precursor therefor is generally in a solid state having a low vapor pressure. It is very difficult to vaporize such a precursor using a known vaporizer, and to feed it into a film-formation chamber.
In addition, even if the relevant vaporization in a vaporizer is possible, the precursor may be deposited inside a pipe connected to the film-formation chamber or in the chamber itself. In such a case, the amount of the fed precursor may not be controlled, or the apparatus may have a problem.
As a perovskite material generally includes two metal elements, accurate control of the amount of each metal material fed into the film-formation chamber corresponds to the control of the relevant film composition, and thus is very important. Therefore, the process of forming a perovskite film using a known film-formation technique such as CVD (chemical vapor deposition) and ALD (atomic layer deposition) has not been sufficiently established for a long period of time.
In recent supercritical film formation, which is anticipated as the next-generation film-formation technique, any reagent which dissolves in a supercritical fluid can be used as a precursor, regardless of the state (i.e., solid, liquid, or gas) of the reagent. Therefore, it can be understood that such a reagent has a potential for solving the above-described problem attendant on the development of the process for forming a perovskite film. Accordingly, methods for feeding such a solid film-formation material as a precursor have been developed (see, for example, Patent Documents 1 to 3).    Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2003-213425.    Patent Document 2: Japanese Unexamined Patent Application, First Publication No. 2003-282556.    Patent Document 3: Japanese Unexamined Patent Application, First Publication No. 2006-144083.
However, the present inventor has recognized that no method or apparatus for performing stationary feeding of a solid film-formation material at a desired speed has been established.